Photodissociation Dynamics of the Ethoxy Radical (C2H5O)†

Photodissociation of the ethoxy (C2H5O) radical is investigated using photofragment translational spectroscopy. The ethoxy radical is generated by photodetachment of C2H5O- and subsequently dissociated by photon absorption in the range of 270-220 nm; no dissociation is seen at higher wavelengths. The photofragment yield (PFY) spectrum is structureless but exhibits abrupt increases in intensity at 260 and 225 nm. The product mass distribution shows that C2H5O dissociates into the vinyl radical (C2H3) and H2O throughout the entire absorption band. We propose that these products are formed by isomerization and dissociation on electronically excited surfaces rather than by internal conversion to the ground state. The translational energy P(ET) distributions for this channel are largely insensitive to photon energy. However, at the two highest photon energies (5.51 and 5.96 eV), a new feature appears at ET e 0.3 eV, which is assigned as production of an excited state of C2H3. I